Mar 12, 2011

List of Drugs Affected by Grapefruit

         Grapefruit and grapefruit juice have the potential to interact with numerous drugs. A number of organic compounds, identified as furanocoumarin derivatives, interfere with the hepatic and intestinal enzyme cytochrome P450 isoform CYP3A4 and are therefore primarily responsible for the interaction. However, bioactive compounds in grapefruit juice may also interfere with P-glycoprotein and organic anion transporting polypeptides (OATPs) either increasing or decreasing bio-availability of a number of drugs. Pomelo (the Asian fruit which was crossed with an orange to produce grapefruit) also contains high amounts of furanocoumarin derivatives.
    Certain chemicals that grapefruit products and citrus fruits contain can interfere with the enzymes that break down (metabolize) various medications in your digestive system. As a result, more medication stays in your body. This can increase the potency of your medication to potentially dangerous levels, causing serious side effects.
    Pomelos and Seville oranges, a type of bitter orange often used to make marmalades and compotes, may have a similar effect. Researchers are identifying other foods that also may interact with medications, so check with your doctor or pharmacist if you have any concerns.


    In 1989 a pharmacological study evaluated the possibility of an interaction between ethanol ingestion and medication with the dihydropyridine calcium channel blocker - felodipine. Grapefruit juice was used as a flavouring additive during the test. The results of study showed several-fold increase of felodipine concentrations compared to results obtained in other investigations of the drug. Additionally, there were lower blood pressure readings and more adverse effects compared to the group of subjects on felodipine alone. Further investigations revealed that grapefruit juice strikingly elevated felodipine bioavailability and could influence its other pharmacokinetic and pharmacodynamic properties.


    Drugs affected by grapefruit juice
    Drug class Major Interactions Minor interactions
    Calcium channel antagonists
    Plendil
    Cardene (Nicardipine)
    Procardia (Nifedipine)
    Nimotop
    Sular
    DynaCirc
    Antiarrhythmics Cordarone
    Multaq

    Statins (HMG-CoA reductase inhibitors) Mevacor (Lovastatin) Lipitor
    Baycol (off the market)
    Immunosuppressants
    Sandimmune (Cyclosporine)
    Prograf
    Rapamune
    Mercaptopurine
    Dissociatives Dextromethorphan
    Sedatives, hypnotics, and anxiolytics Buspar Halcion
    Versed
    Valium (Diazepam)
    Sonata (Zaleplon)
    Alprazolam
    Other psychotropics
    Tegretol (Carbamazepine)
    Desyrel
    Serzone
    Seroquel
    Fluvoxamine
    Antihistamines Seldane (off the market)
    Diphenhydramine (partially)
    Hismanal (off the market)
    Claritin (Loratadine)
    HIV protease inhibitors
    Invirase
    Norvir
    Viracept
    Agenerase
    Hormones
    Ortho-Cept (Ethinyl estradiol)
    Depo-Medrol (Methylprednisolone)
    Other drugs
    Viagra
    Propulsid
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